(1) Field of the Invention
The apparatus of the invention relates to the field of optically characterizing the structure of a surface, which, for example, is useful in a board or sheet production line for inspecting the quality of a board or sheet product.
A known apparatus is disclosed in U.S. Pat. No. 3,694,658 to Morvue, presenting diffuse light transversal to the element under inspection and its direction of which t is conveyed, wherein light reflected off a surface of the element under inspection is picked up by a plurality of optical fibers. A conveyor conveys the board or sheet past an elongated light source, such as a fluorescent light tube, located in a first position over the board or sheet, while a light detector is located over the board or sheet in a second position spaced from the first position in a direction of conveyance of the board or sheet. An elongated aperture or baffle is arranged between the light source and the detector, such that the detector may only receive such light from the light source that has been reflected off or scattered by the surface of the board or sheet and that has a significant directional component corresponding to the direction of conveyance of the board or sheet.
(2) Description of Related Art
Other known art is disclosed in U.S. Pat. No. 5,252,836 to US National resources, illustrating surface inspection using collimated light propagating in the direction in which an element under inspection is conveyed.